Heart failure with preserved ejection (HFpEF) is rapidly coming the most common form of congestive heart failure, and there are currently limited effective therapies. The lack of effective therapies underscores the urgent need to identify novel therapeutic targets to treat HFpEF. A potential treatment target is abnormal ventricular filling during diastole or diastolic dysfunction due to cardiac fibrosis. While anti-fibrosis therapies hav a powerful effect on diastolic dysfunction, such therapies in humans have yielded disappointing results. Our proposal offers a novel approach to this problem by focusing on the activation of pro-fibrotic signaling downstream of transforming growth factor receptor beta (TGF?by the stretch sensitive potassium channel TREK-1. Mice lacking TREK-1 develop exaggerated cardiac hypertrophy in response to pressure overload yet still maintain normal diastolic function. Our preliminary data suggest that this phenotype is explained by altered fibroblast activity and disruption of TGF?ignaling. The overall objective of this proposal is to investigate how TREK-1 regulates cardiac fibrosis in response to pressure overload and to allow me to develop the skills to become an independent investigator. Our central hypothesis is that the loss of TREK-1 function attenuates cardiac fibrosis through disrupted TGF?ignaling and diminished fibroblast activation. We will address this hypothesis, using the following approach: 1) we will determine how TREK-1 affects fibroblast function and differentiation using cardiac fibroblasts isolated from TREK-1 knockout mice and by utilizing a myocardial infarction model, 2) we will determine how TREK-1 affects TGF?ediated signaling by biomechanical stretch using an in vitro cellular stretch model and 3) we will investigate how the loss of TREK-1 in fibroblasts affects response to cardiac injury using a conditional TREK-1 knockout mouse. The proposed experiments will generate insights into the development of diastolic dysfunction due to cardiac fibrosis and novel targets to treat HFpEF. Over next several years, I hope the following skills: 1) generation and utilization of animal models of cardiac disease, 2) molecular biology techniques, 3) methods to study cardiac mechanotransduction and 4) personnel management. These skills coupled with the data obtained during the award period will allow me to achieve my long-term goal of becoming an independent investigator focused on identifying molecular mechanisms underlying HFpEF. My mentor for this award proposal is Dr. Howard Rockman, who is a leader in the field of molecular biology and has extensive experience as a research mentor. Moreover, my mentorship team, my clinical experience in treating heart failure patients and the training environment at Duke University Medical Center is optimal for achieving both the career development and scientific objectives outlined this proposal.